Could eventually allow doctors to see if cancer has spread from its original site faster than ever

Harvard and MIT researchers
have developed a tool that is capable of identifying single cancer cells within
a blood sample.

Mehmet
Toner, study leader and a professor of biomedical engineering at Harvard
Medical School, and Brian Wardle, an MIT associate professor of aeronautics and
astronautics, have created an instrument that could eventually allow doctors to
see if cancer
has spread from itsoriginal
site faster than ever.

Circulating
tumor cells, which are cancer cells that escaped from the original tumor, can
be difficult to find because a 1-milliliter sample of blood, which has tens of
billions of normal blood cells, only contains "several" circulating
tumor cells.

"Of
all deaths from cancer, 90 percent are not the result of cancer at the primary
site," said Wardle. "They're from tumors that spread from the
original site."

In
response to this dilemma, Toner created a new microfluidic device capable of detecting
these circulating tumor cells. He originally designed the device
four years ago, and it worked by allowing a patient's blood sample to travel
past tens of thousands of little silicon posts that are covered with
antibodies. These antibodies stick to tumor cells, and any cancer cells that
touch the silicon posts are caught and held in place. The problem with this
prototype was that certain cells might never come in contact with the silicon
posts at all.

Toner has
since made changes to the device with the help of Wardle, making it eight times
better than the original. The microfluidic device now features porous posts
instead of those that are solid, which were made using carbon nanotubes. The
carbon nanotubes are small, hollow cylinders that have walls made of carbon
atom lattices. A "forest" of these nanotubes have 10 billion to 100
billion carbon nanotubes per square centimeter, and are 99 percent air and less
than 1 percent carbon.

Much like
the original version, these carbon nanotubes are coated with antibodies that
capture particular cancer cells. The device is also customizable, allowing
researchers to attach different antibodies to the carbon nanotubes or adjusting
the space between the nanotubes in order to catch objects of different sizes,
from circulating tumor
cells to viruses.

The
porous posts allow cells to run through them, much like a filter, offering
greater chance of catching the cells researchers are looking for.

Toner and
Wardle's device is currently being tested in hospitals and is expected to be
made available commercially "within the next few years." In addition,
researchers hope to adjust the device for HIV diagnosis as well.